1. Field of the Invention
This invention relates to an automatic analyzing apparatus for automatically effecting chemical analysis on a sample of blood, urea or the like.
2. Description of the Prior Art
In an automatic analyzing apparatus heretofore proposed, a sample and a reagent dependent on measurement items are distributed into a reaction vessel to be transferred along a given path to obtain a reaction liquid and the light absorption degree of the reaction liquid is measured through the reaction vessel. Such automatic analyzing apparatus for measuring the light absorption degree of the reaction liquid through the reaction vessel has the drawback that the irregular light absorption degree of the reaction vessel per se is influential to the analytical accuracy.
In order to obviate such drawback, another automatic analyzing apparatus has been proposed which can measure the light absorption degree of the reaction vessel prior to the analysis and correct the light absorption degree of the reaction liquid. Such automatic analyzing apparatus function to repeatedly wash and use a reaction vessel set beforehand to the apparatus and measure the light absorption degree of the reaction vessel and of the reaction liquid at the same photometric unit, thereby lowering the process ability of the apparatus. Particularly, the repeated use of the reaction vessel provides the disadvantage that the change of the light absorption degree of the reaction vessel due to the change of the physical condition such as contamination, damage or the like produced when the reaction vessel is repeatedly used and the change of the light absorption degree after the lapse of time could not be corrected. As a result, after the lapse of long times, the analytical accuracy of the apparatus becomes degraded. Particularly, the analytical accuracy of an analytical method which makes use of an end point process of measuring the light absorption degree of the reaction liquid on the basis of the light absorption degree of a reagent becomes considerably degraded.
Meanwhile, a further automatic analyzing apparatus has been proposed which can measure the light absorption degree of the reaction liquid through a reaction vessel which is disposable and discarded. In such apparatus, the reaction vessel is different for every one sample, so that the liquid absorption degrees of these reaction vessels are different from each other. The disposable reaction vessel is usually formed of light transmission plastics such as polymethyl pentene resin or the like whose slight change in size, dimension, material composition, shaping condition or the like makes the light absorption degree of the reaction vessel irregular. In order to limit such irregular light absorption degree within a given accuracy, use must be made of apparatus which is complex in construction, sensitive in operation and expensive.